This document discusses best practices for developing RESTful APIs and backend services for mobile applications. It recommends using Java, Maven, Spring, Jersey, and Protocol Buffers. Protocol Buffers provide a compact data interchange format that is faster than JSON and more widely supported than other protocols. The document provides an example of implementing authentication, API throttling, caching, testing, and error handling in a RESTful service using these technologies.

1. Yaroslav Pogrebnyak Software Developer, Ciklum [email_address] www.pogrebnyak.info Rapid Java Backend & API Development for Mobile Devices

2. Devices & Apps Hell How to interact? A lot of work for backend developers ]:->

3. Device ↔ Server interaction

4. How to define API? HTTP + MediaType + ... = REST? It Depends! - URI - Media-Type: xml, json, etc - Operations: create, update, delete, … - Custom conventions GET http://example.com/users/ POST http://example.com/users/ DELETE http://example.com/users/42

5. Data Interchange Protocols PlainText, XML, JSON, ProtocolBuffers , BERT, BSON, Thrift, MessagePack, Custom Protocol... 1. Size 2. Performance 3. Usability 4. Platforms

6. 68 bytes: { &quot;status&quot; : &quot;OK&quot; , &quot;response&quot; : { &quot;id&quot; : 42 } } 5 bytes (hex dump): 0801 102a 0a JSON vs XML vs Protocol Buffers 119 bytes: <? xml version=&quot;1.0&quot;?> < message > < status >OK</ status > < response > < id >42</ id > </ response > </ message >

7. HTTP POST /api/register/ Content-Type: application/x-protobuf Accept: application/x-protobuf serialize deserialize HTTP 200 OK Content-Type: application/x-protobuf Content-Length: 5 serialize deserialize Protocol Buffers scenario

8. Implementation

9. API requires strength , Java-world's advantage: Static Typing

10. Java + Maven + Spring + Jersey + Protocol Buffers

11. Create project Jersey Simple Webapp $ mvn archetype:generate -DarchetypeCatalog= http://download.java.net/maven/2 Spring + Jersey $ mvn archetype:generate -DarchetypeCatalog= http://seratch.github.com/mvn-repo/releases DIY $ cd project $ vim pom.xml :) Minimalistic Secret Template :) http://pogrebnyak.info/ciklum/spring_jersey_gpb.zip

12. Protocol Buffers Schema package myapi ; // POST /api/register message RegisterRequest { required string login = 1; optional string email = 2; } // Response message RegisterResponse { enum Status { SUCCESS = 0; ALREADY_EXISTS = 1; } required Status status = 1; required string id = 2; }

13. Conventions /some/endpoint Request: message Name Request { … } Response: message Name Response { enum Status { … } required Status status = 1; ... }

14. Configuration Implement Protocol Buffers Serializer/Deserializer for Jersey @Provider @Component @Consumes ( “application/x-protobuf” ) public class ProtobufMessageReader implements MessageBodyReader<Message> { // ... @Provider @Component @Produces ( “application/x-protobuf” ) public class ProtobufMessageWriter implements MessageBodyWriter<Message> { // ...

15. applicationContext.xml DataSource & transaction management web.xml Jersey Spring Servlet & Spring context listeners Protofile & package for generated files Controller classes Services & dao Other Stuff Protobuf serializers pom.xml project configuration

16. Jersey Сontroller Example @Component @Transactional @Path ( &quot;/api&quot; ) public class ApiController { @Autowired private ClientUserService userService; @POST @Path ( &quot;/register&quot; ) public RegisterResponse register( RegisterRequest r) { User user = new User(r.getLogin()); userService.createUser(user); return RegisterResponse . newBuilder () .setStatus(Status.Success) .setId(user.getId()) .build(); } }

18. Thank you! Yaroslav Pogrebnyak [email_address] www.pogrebnyak.info Presentation: http://pogrebnyak.info/ciklum/spring_jersey_gpb.ppt Sample project: http://pogrebnyak.info/ciklum/spring_jersey_gpb.zip